The invention relates to an improved line mole trap used in the cleaning of tubular targets by water-blasting techniques. Tubular targets generally include tubular members such as pipes, square tubes, cylindrically-shaped containers, conduit, and other hollow members and chambers having at least one opening. However, the invention is particularly concerned with a device attachable to various-sized pipes that can protect an operator from the hazardous conditions associated with the emergence of a line mole from the entrance of a pipe.
One of the most hazardous conditions encountered in water-blasting results from the use of hydraulic line mole. A hydraulic line mole consists of a body containing several orifices attached to the end of a high pressure flexible hose. The attached line mole is inserted into a tubular target and directs high pressure streams of liquid against the interior surfaces of the target to scour these surfaces clean. Some of the orifices in the line mole body are directed rearward. These rear-facing orifices provide a thrust to the line mole, causing it to move forward, pulling the flexible supply hose behind it. Line mole forward speed is regulated by restraint applied to the flexible hose. The tubular target is cleaned by allowing the line mole to advance.
Quite often during the cleaning of the tubular target the line mole is retracted by applying a pull to the supply hose to overcome the thrust of the rearward facing jets. When the line mole is retracted by an operator standing near the entrance of the tubular target, a slight misjudgment might result in the line mole being withdrawn completely from the tubular target. Under such circumstances the operator is exposed to the line mole's high pressure liquid jets, and injury or death may result. Under certain other conditions, the tubular target may become plugged during cleaning. When plugging occurs the volume of water inside the tubular target ahead of the line mole increases, forcing the line mole to move backward. This displacement results in similar hazardous exposure to the operator.
To protect the operator from the high pressure jet streams the line mole must be encapsulated in a protective device as it emerges from the tubular target to dissipate the energy of the high pressure fluid streams before it endangers the operator. Several schemes have been tried. Devices have been built to prevent the exit of the line mole from the tubular target, but those devices have several drawbacks. First, they usually fit only one size tubular target. Secondly, those devices do not allow the tubular target to be cleaned all the way to the end. Finally, they are very slow and cumbersome to install, thereby tempting the operator to forego their use. The line mole trap of the present invention overcomes these deficiencies.